Automotive topcoats must be able to resist damage caused by environmental factors, such as fallout, ultraviolet radiation and high humidity. It must also be able to resist damage caused by scratch and mar resulting from impact, rubbing or abrasion that results in visible scrapes or marring on the surface.
From the perspective of material mechanics, excellent scratch and mar resistance requires the topcoat matrices to have high yield strength in order to minimize plastic flow and necessary elastic strain to avoid brittleness, thereby preventing matrix fracture. Traditionally, automotive topcoats contain thermoplastic resins, most often comprising acrylic, urethane and/or ester polymer chains, which are cross-linked by thermosetting units such as melamine formaldehyde and epoxide in the final thermal curing step. These viscoelastic crosslinking networks are chosen because they offer not only high thresholds of yield-strength for strong abrasion resistance but also environmental durability and optical transparency. However, simple modification of the polymer chain structures and cross-linker to improve polymer properties is limited by the cost of making such improvements, as traditional polymers require the use of expensive organic cross-linkers bearing multiple reactive functional groups and macromers or prepolymers. In addition, mechanical properties at the surface of the topcoat are often quite different from that in the bulk of the coating as the use of multi-vinyl cross-linkers typically result in a harder bulk phase, which consequently limits the ability to achieve the desired properties. It has therefore been traditionally difficult to tune the ductility of anti-scratch coatings while maintaining a high enough mechanical strength sustained by dense cross-linking and strong chain interactions, making it difficult to obtain a coating matrix that is hard but non-brittle as well.
There is therefore a need to provide a polymer matrix, polymer composition and polymer coating that overcomes or at least ameliorates, one or more of the disadvantages described above. There is also need to provide a method of forming such polymer matrix, polymer composition and polymer coating, as well as a use of the polymer matrix, polymer composition and polymer coating.